All righty. Leave out Peashooter and Tangle Kelp, and bring Potato Mine and Squash instead.
Right off the bat, plant a Sunflower (duh). Keep planting as many of them as you can. When the first few zombies show up, plant Potato Mines and Squashes waaaaay in front of them. They'll die on impact with either of those plants. This should buy you enough time to get 10 Sunflowers up (4 in back on each side, two in pool). Once you've got the Sunflowers, start planting Wall-nuts ad try to get a Repeater in every row. You'll especially need Wall-Nuts in the pool. Plant Snow Peas to back up the Repeaters, and make sure the Wall-Nuts are far up the lawn so the pole vaulters won't have time to get anywhere after they jump. Plant a second row of Repeaters if you have time.
Good luck.
I use the Beginning Strategy all the time and it works well and it's a cheep starting def.